A truth reference system includes a truth source that is an independent sensor, measuring device or other source of spatial information with an accuracy known to be within desired parameters or bounds. The truth source can be used to assess the performance of a navigation system, to calibrate it, to correct its performance, and so on. For example, in order to qualify a new navigation system such as for an aircraft, both the truth source and the new navigation system record navigation information while the aircraft is in operation. After the flight (post-mission) or even during flight, the data from the new navigation system is analyzed and compared against the data from truth source in order to verify whether the new navigation system performed properly and up to desired performance specifications Likewise, the performance of satellites, naval navigation systems, tanks, trains, automobile, map-creation systems, etc., may be evaluated in a similar manner.